1. Field of the Invention
The invention relates generally to the field of automatic drivers for fasteners. More specifically, the present invention relates-to an apparatus for driving fasteners that is automatic and controllable. Yet more specifically, the present invention relates to a device for driving fasteners, where the apparatus delivers a specified torque. Yet even more specifically, the present invention relates to an automatic apparatus where the torque delivered is controllable from about 1 in-lb up to about 50 in-lb.
2. Description of Related Art
Many prior art devices exist that are capable of driving fasteners apertures, such as threaded bolt holes and the like. These tools typically require the user to activate a switch or a trigger to activate the device. Further, some prior art devices rely on power sources such as compressed air to drive the associated motor, which can limit the applicability of a device since producing compressed air requires space for a compressor and is generally impractical. Other devices that employ electrical motors produce an output whose speed and torque can vary and is not precisely controllable or not controllable at all. However many instances where it is required to employ a rotary tool, the ability to control the speed and torque is important. Some fasteners require that they be installed to a specified torque, and it is important that how much the fastener has been torqued be easily verified by the operator of the device.
Some of these devices include means to measure the rotational force, or torque, exerted by the particular device. These means range from monitoring the current consumed by the device, pressure sensors applied to working parts of the device, and included various sensors within the device. Examples of prior art devices useful for driving fasteners can be found in U.S. Pat. Nos. 4,487,270, 4,887,499, 6,424,799, 4,571,696, and 4,502,549.
Therefore, there exists a need for an apparatus and a method for securing fasteners that is reliable, accurate, and can precisely torque a fastener to a specified torque. An additional need exists for a tool to be durable, hand held, and provide an indication the preciseness of the directly torqued value.